1. Field of the Invention
The present invention relates to the field of ankle braces, and in particular to an ankle brace which immobilizes the ankle against inversion or eversion while permitting plantoflexion and dorsiflexion.
2. Description of the Prior Art
The ankle is a part of the body which is one of the most prone to injury. Once an ankle injury has occurred, it is usually necessary or desirable to immobilize the ankle in a manner to permit healing of the ankle. Various approaches have been proposed in the prior art to support the ankle during the healing process, as well as for other purposes including to prevent further injury.
Among athletes, injuries of the ankle such as by ankle sprains may be second in frequency only to injuries to the knee. In a recent survey of injuries suffered by various college football teams during 1982, injuries of the ankle were second in occurrence only to knee injuries. Of 2761 injuries to the athletes surveyed. 469 or 16% of the injuries were of the ankle, as compared to 21% of the injuries having occurred to the knee. Of course, the freguency of ankle injuries will vary among the different teams and sports. Also, injuries to the ankle occur in a variety of settings in addition to athletic endeavors. The important point is that injuries to the ankle are common, and there is therefore a significant concern for protecting the ankle during recovery and against further injury.
Considerable disagreement currently exists as to the advisability and actual effectiveness of using tape in the treatment or prevention of ankle injuries. Adhesive tape has been used by persons, including many trained professionals, for protecting the ankle, although many disadvantages appear to exist. The application of tape requires the time of a trained person, and is expensive both in requiring the use of trained personnel and in the cost of the tape itself. The support afforded by the tape may reduce by 40% after ten minutes of vigorous activity. Repeated use of ankle taping may lead to irritation to the bare, movable skin to which it is applied. Also, moisture collecting under the tape will cause the tape to loosen, thus diminishing its effectiveness.
Perhaps of equal concern in the usage of adhesive tape is that the presence of the tape can lead to a weakening of the ankle, particularly the supporting muscle tendons. The taping often replaces the practice of thoroughly exercising the ankle joint, and may give the person a false security which eventually becomes a psychological crutch. Moreover, the rigid taping of the ankle locks the subtalar joint, thereby increasing stress to the knee joint.
Another alternative for the protection of the ankle is the use of ankle wraps, such as elastic bandages. However, the use of such bandages carries many of the same disadvantages as described with respect to adhesive tape. In addition, such wraps may loosen considerably, perhaps in the range of 34-77%, thus reducing the effectiveness of the wrap for the intended purpose of protecting the ankle. An elastic wrap designed particularly for supporting the ankle is described in U.S. Pat. No. 3,506,000, issued to Baker on Apr. 4, 1970. Another device constructed for this purpose is described in U.S. Pat. No. 3,674,023, issued to Mann on July 4, 1972. The Mann device comprises a heel boot shaped much like the rear half of a boot and mounted onto the foot by straps utilizing VELCRO strips for attachment. An additional, informative discussion of the prior art in this field is also included in the Mann patent.
A third alternative that has surfaced in the prior art is the employment of reusable ankle braces. Such braces have the advantage of being able to be used many times, thus minimizing the cost factor. Also, some of the disadvantages of adhesive tape or elastic bandages are overcome by these braces. However, prior art braces have typically involved only minimum of consideration to the anatomical structure and functioning of the ankle. As a result, many braces act to diminish or eliminate certain types of movement of the ankle while the braces are in use. Many of the prior art braces have also been quite bulky and uncomfortable, and in certain instances have not done an effective job of protecting the ankle as desired.
There are currently two types of ankle braces that are prevalent in the market. A first type is the lace-up variety such as that available from Tru-Fit Marketing Corporation, 680 Lynnway, Lynn, Mass. 01905. The Tru-Fit ankle support is made of vinyl with nylon reinforced webbing and extends from the instep to above the ankle. The support laces up the front much like a high top boot or shoe. A similar type of ankle support is disclosed in U.S. Pat. No. 4,280,488, issued to Polsky on July 28, 1981.
An ankle supporter is discussed in U.S. Pat. No. 15,446, issued to Hamilton on June 17, 1922. The Hamilton supporter includes side members made of leather, felt, woven fabric or other suitable material having flexibility to permit the sides to be pulled over the ankle portions from the rear of the ankle at which the sides are integrally joined. The side members include padding to provide support for the narrower portions of the ankle structure, and the whole unit is secured to the ankle by lacing over the front of the foot. A similar device which is strapped onto the foot and wraps over the sides of the ankle from the rear is disclosed in U.S. Pat. No. 4,133,311, issued to Karczewski on Jan. 9, 1979.
A second type of brace which is currently common in the market is available from Aircast Incorporated of Summit, N.J. This brace may be covered by any of U.S. Pat. Nos. 3,955,565, 4,280,489 and 4,287,920. The Aircast brace includes a bottom pad and a pair of upwardly extending side members which are secured to either side of the ankle by VELCRO strips which wrap around the ankle or leg. The Aircast design is fairly simple, and apparently relies on the vertically extending pads to protect the ankle from inversion and eversion. However, the brace is relatively bulky and therefore may not be useful with certain types of footwear, particularly with high top shoes. Also, the Aircast brace includes a pivot point at the connection of the bottom pad with the side members, thus providing for pivoting at an anatomically incorrect location at the bottom of the foot. This leads to a restriction of dorsiflexion and plantoflexion of the ankle.
A simplified ankle brace is described in U.S. Pat. No. 112,952, issued to Niswander on Mar. 21, 1871. The Niswander ankle brace includes a stirrup formed of sheet metal and configured to extend under the foot at about the heel. The stirrup curves upwardly a short distance along the inside of the foot, and on the outside extends upwardly to above the ankle bone. A side plate which is laced to the lower part of the leg is connected with the side plate by a rivet, thereby allowing for pivoting motion of the side plate relative the stirrup.
An ankle brace and supporter is shown in U.S. Pat. No. 830,894, issued to Garrod on Sept. 11, 1906. The Garrod device includes pairs of longitudinal members positioned on each side of the leg and pivotally mounted to a plate received under the heel of the foot. The longitudinal members are strapped to the leg. As with certain other devices, the pivoting motion permitted by this device is inappropriate to the ankle structure since the pivot is positioned below the foot.